Thx. I'm also the one that upload the video from iPhone, and I do know whether this video is horizontal or not, can I do something in the iPhone before I'm uploading it without re-encoding it?
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shemSep 17 '12 at 9:58

Maybe. Encoding would be something that is decently integrated into the software, so there's a chance you can't do anything but re-encode. stackoverflow.com/questions/2208522/…: though you could likely find an only service that you could use as filter before you upload. There are several suggestions around (comments): youtube.com/watch?v=smVIRDfcEvU but they are targeting Quicktime so that may be a "fix" within the problem rather than affecting the problem itself.
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Matt WhippleSep 17 '12 at 11:31